﻿using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.Serialization.Json;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace DLL
{
    public class JsonHelp
    {
        public JsonHelp()
        {
            //
            // TODO: Add constructor logic here
            //
        }
        /// <summary>
        /// 把对象序列化 JSON 字符串 
        /// </summary>
        /// <typeparam name="T">对象类型</typeparam>
        /// <param name="obj">对象实体</param>
        /// <returns>JSON字符串</returns>
        public static string GetJson<T>(T obj)
        {
            //记住 添加引用 System.ServiceModel.Web 
            /**
             * 如果不添加上面的引用,System.Runtime.Serialization.Json; Json是出不来的哦
             * */
            DataContractJsonSerializer json = new DataContractJsonSerializer(typeof(T));
            using (MemoryStream ms = new MemoryStream())
            {
                json.WriteObject(ms, obj);
                string jsonString = Encoding.UTF8.GetString(ms.ToArray());
                string pattern = @"\\/Date\((\d+)\+\d+\)\\/";
                MatchEvaluator matchEvaluator = new MatchEvaluator(ConvertJsonDateToDateString);
                Regex reg = new Regex(pattern);
                jsonString = reg.Replace(jsonString, matchEvaluator);
                return jsonString;
            }
        }
        /// <summary>
        /// 把JSON字符串还原为对象
        /// </summary>
        /// <typeparam name="T">对象类型</typeparam>
        /// <param name="jsonString">JSON字符串</param>
        /// <returns>对象实体</returns>
        public static T ParseFormJson<T>(string jsonString)
        {
            T obj = Activator.CreateInstance<T>();
            string pattern = @"\d{4}-\d{2}-\d{2}\s\d{2}:\d{2}:\d{2}";
            MatchEvaluator matchEvaluator = new MatchEvaluator(ConvertDateStringToJsonDate);
            Regex reg = new Regex(pattern);
            jsonString = reg.Replace(jsonString, matchEvaluator);
            using (MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(jsonString)))
            {
                DataContractJsonSerializer dcj = new DataContractJsonSerializer(typeof(T));
                return (T)dcj.ReadObject(ms);
            }
        }
        /// <summary>
        /// 将Json序列化的时间由/Date(1304931520336+0800)/转为字符串
        /// </summary>
        private static string ConvertJsonDateToDateString(Match m)
        {
            string result = string.Empty;
            DateTime dt = new DateTime(1970, 1, 1);
            dt = dt.AddMilliseconds(long.Parse(m.Groups[1].Value));
            dt = dt.ToLocalTime();
            result = dt.ToString("yyyy-MM-dd HH:mm:ss");
            return result;
        }
        /// <summary>
        /// 将时间字符串转为Json时间
        /// </summary>
        private static string ConvertDateStringToJsonDate(Match m)
        {
            string result = string.Empty;
            DateTime dt = DateTime.Parse(m.Groups[0].Value);
            dt = dt.ToUniversalTime();
            TimeSpan ts = dt - DateTime.Parse("1970-01-01");
            result = string.Format("\\/Date({0}+0800)\\/", ts.TotalMilliseconds);
            return result;
        }


    }
}
